Etiology

An etiological factor or factors can be identified in more than 90 % of cases and should be actively sought, because it may determine the treatment and prognosis (Smith et al. 1998; Santora and Rukstalis 2001). In apparently idiopathic cases, the cause may have been overlooked or obscured by the necrotizing disease process.

Any process where a virulent, synergistic infection gains access to the subcutaneous tissue of the perineum may serve as the point of origin. The cause of infection may be from a urogenital, anorectal, cutaneous, or ret-roperitoneal origin. The urogenital area is the most common etiologic site, where urethral stricture disease is at the top of the list (Edino et al. 2005). Knowledge of the anatomy of the perineum, urogenital area, and lower abdomen is necessary to understand the etiology and pathogenesis of this fulminant infection.

The possible causes of Fournier's gangrene are listed in Table 6.1. Infection may originate in any of the listed areas, with extension to the fascial planes leading to a proliferating fasciitis (Jones et al. 1979; Karim 1984; Walker et al. 1984; Walther et al. 1987; Baskin et al. 1990; Sengoku et al. 1990; Gaeta et al. 1991; Attah 1992; Paty and Smith 1992; Theiss et al. 1995; Benizri et al. 1996; Hejase et al. 1996; Fialkov et al. 1998; Corman et al. 1999; Eke 2000; Kilic et al. 2001; Ali 2004; Jeong 2004; Yeniyol et al. 2004; Edino et al. 2005).

Although Fournier's gangrene is predominantly a condition of the older male, it may occur at any age, and approximately 10% of cases occur in females (Kilic et al. 2001; Quatan and Kirby 2004). Specific causes in women include pudendal nerve block or episiotomy for

Table 6.1. Causes of Fournier's gangrene

Urogenital

Urethral stricture

Indwelling transurethral catheter

Prolonged or neglected use of condom catheter

Urethral calculi

Urethritis

Transurethral surgery

Infection of periurethral glands and paraurethral abscess

Urogenital tuberculosis

Urethral cancer

Prostate biopsy

Prostatic massage

Prostate abscess

Insertion of penile prosthesis

Constriction ring device for management of ED

Iatrogenic trauma

Cauterization of genital warts Circumcision

Manipulation of longstanding paraphimosis

Noniatrogenic trauma

Animal, insect, or human bite

Scrotal abscess

Infected hydrocele

Hydrocelectomy

Vasectomy

Balanitis

Phimosis

Anorectal

Ischiorectal or perianal or intersphincteric abscess

Rectal mucosal biopsy

Banding ofhemorrhoids

Anal dilatation

Cancer of sigmoid or rectum

Diverticulitis

Rectal perforation by foreign body Ischemic colitis Anal stenosis

Cutaneous

Hidradenitis suppurativa

Folliculitis

Scrotal pressure sore

Post-scrotal surgery wound infection

Cellulitis of scrotum

Pyoderma gangrenosum

Femoral access for intravenous drug users

Retroperitoneal causes

Psoas abscess

Perinephric abscess

Appendicitis and appendix abscess

Pancreatitis with retroperitoneal fat necrosis

Other

Inguinal hernia repair Filariasis in endemic areas Strangulated Richter hernia vaginal delivery, septic abortion, hysterectomy, and Bartholin and vulval abscess (Roberts and Hester 1972; Addison et al. 1984).

A prominent feature of patients with Fournier's gangrene is that most of them have an underlying systemic disorder causing vascular disease or suppressed immunity, which increases their susceptibility to polymicro-

Table 6.2. Underlying disorders in patients with Fournier's gangrene

Diabetes mellitus Chronic alcoholism Malnutrition Obesity Liver cirrhosis Poor personal hygiene Immunosuppression: Chronic steroid use Organ transplantation Chemotherapy for malignancy HIV/AIDS Tuberculosis Syphilis bial infection (Table 6.2). Fournier's gangrene is often a marker of an underlying disease such as diabetes melli-tus, urogenital tuberculosis, syphilis, or HIV.

Diabetes mellitus is the most common associated underlying systemic disease, affecting two-thirds of patients with Fournier's gangrene. Diabetic patients have a higher incidence of urinary tract infections, due to cystopathy with urinary stasis (Baskin et al. 1990). Hyperglycemia decreases cellular immunity by decreasing phagocytic function. It retards chemotaxis of leukocytes to the site of inflammation, neutrophil adhesion, and intracellular oxidative destruction of pathogens. Wound healing is also retarded due to defective epithe-lialization and collagen deposition (Hejase et al. 1996; Nisbet and Thompson 2002). Apart from hyperglyce-mia, diabetic patients also have microvascular disease, which contributes significantly to the pathogenesis. Although diabetes mellitus increases the risk for development of Fournier's gangrene, it does not increase the mortality (Baskin et al. 1990; Benizri et al. 1996; Hejase et al. 1996; Yeniyol et al. 2004).

Chronic alcoholism, malnutrition, liver cirrhosis, poor personal hygiene, and personal neglect are quite common in patients with Fournier's gangrene (Benizri et al. 1996; Hejase et al. 1996; Yeniyol et al. 2004). Other conditions causing depressed immunity that may predispose to the development of Fournier's gangrene include chronic steroid use, organ transplantation, chemotherapy for malignancies such as leukemia, as well as HIV infection (Paty and Smith 1992; Elem and Ranjan 1995; Heyns and Fisher 2005).

The rising incidence of HIV is paralleled by a rising incidence of Fournier's gangrene, especially in Africa. Fournier's gangrene may be the first presenting condition in patients with HIV infection (McKay and Waters 1994; Elem and Ranjan 1995; Roca et al. 1998; Heyns and Fisher 2005). Risk factors include a CD4 count under 400, chemotherapy for Kaposi's sarcoma, and femoral access for the administration of intravenous drugs. HIV-positive patients with Fournier's gangrene present at a younger age and have a wider spectrum of causative bacteria (McKay and Waters 1994).

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